The long-term objective of this project is the development of highly specific clinical diagnostic tests for the detection and monitoring of patients with gammopathies. Gammopathies are a group of malignant or pre-malignant diseases characterized by the secretion of monoclonal immunoglobulins ("paraproteins"), and include multiple myeloma, amyloidosis AL, and Waldenstrom's macroglobulinemia. Current diagnostic tests generally measure malignant plasma cells and their secreted paraprotein by staining for their immunoglobulin isotype or light chain usage. Although frank malignancies are easy to identify and quantify, there are many cases that are diagnostically challenging. Identifying small numbers of malignant cells or their secreted paraprotein, when dispersed amongst other normal cells or immunoglobulins, is often highly inaccurate or impossible. We recently discovered a new, highly specific manner in which to identify paraproteins and the malignant cells that secrete them. Our finding opens the way for creating new clinical diagnostic assays capable of identifying the "needle" (immunoglobulins secreted by malignant cells) from the "haystack" (all other immunoglobulins, secreted by normal plasma cells). We recently discovered that paraproteins can be distinguished from other immunoglobulins based on the antigens to which they bind. Paraproteins do not bind to random antigens, as previously had been assumed. For example, we discovered that approximately one-third of paraproteins specifically bind to HCMV antigens. This new finding will likely have implications into the pathogenesis of the disease. In this Phase I proposal, however, we are focused on translating our discovery to practical clinical diagnostic tests that will help us in patient management. We propose to create new probes for malignant plasma cells and their secreted paraproteins using protein lysates or peptides derived from HCMV, as a proof-of-principle prototype. Additional antigens will be added as part of Phase II, to create a comprehensive panel. These antigen probes will be optimized and validated as reagents for immunofixation testing (Aim 1, measuring the paraprotein) and immunoflourescent cell marker tests (Aim 2, measuring malignant cells). Probes comprised of antigen, specific for a patient's paraprotein, will represent a quantum leap improvement in diagnostic specificity over current methods. Multiple myeloma and amyloidosis AL are often lethal diseases, caused by cells that grow excessively or in an unchecked fashion. We recently discovered an unexpected common feature amongst the malignant cells, facilitating the development of new, highly specific tests for low levels of disease. This project is a proof-of-principle test, to optimize and validate new highly specific assays for detecting malignant cells or their secreted proteins for these diseases. These tests will thereby improve patient treatment and potentially facilitate new therapeutic approaches to patient treatment. [unreadable] [unreadable] [unreadable]